The subject matter disclosed herein relates to valves and valve technology with particular discussion about an apparatus that can aid in both setting and verifying a set point on a valve assembly.
Valve assemblies integrate several components that cooperate together to regulate flow of a working fluid. Pressure relief valves and other safety valves, for example, use a spring (and/or like resilient member) in a compressed state to maintain the valve assembly in a closed position. This spring exerts a spring force to locate a disc element in contact with a nozzle element to prevent flow of the working fluid through the device. In operation, the spring force correlates with a operating pressure for the working fluid that acts against the disc element. This operating pressure is also called the set point. When the pressure of the working fluid reaches (and/or surpasses) the set point, the disc element may move relative to the nozzle element to an open position that allows the working fluid to flow through the device.
Values for the set point often depend on factors specific to the application that incorporates the valve assembly. It is not uncommon for installation of the valve assembly, e.g., into a process line and/or on a pressurized vessel, to include steps to set the compressed state of the spring to match the set point for the application. Management of the application, as well as regulations and/or public policy, may also require periodic evaluation to assess, in situ, the operation of the valve assembly. For devices including pressure relief valves and safety valves, this assessment finds particular benefit because under ordinary operating conditions, these types of valves typically remain in the closed position and rarely, if ever, move from the closed position to the open position. The lack of movement may cause the set point to migrate away from the original settings (e.g., the compressed state of the spring) that the valve assembly had during installation. The evaluation procedures can ensure that the value for the set point of the valve assembly remains at a certain value or within a certain range.
Conventional devices are known that address the set point on valve assemblies. These devices can apply a load to the spring member, for example, in a direction that corresponds to movement of the disc element relative to the nozzle element to change the valve assembly from the closed condition to the open condition. Unfortunately, these conventional devices are generally only useful to either set or test the set point, but not both. For pressure relief valves that utilize large springs and/or springs that generate high spring forces, this shortcoming in the conventional devices requires use, storage, and maintenance of several different large, unwieldy devices on site to accomplish the tasks necessary to set and to verify the set point for these types of valve assemblies.